JP2003002042A - Air conditioner for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a refrigerant from being held in a pipe connected to an evaporator in the rear side when performing air-conditioning only in the front side. SOLUTION: In an air-conditioner for an automobile, in which a room temperature is separately adjustable in the front side and in the rear side, a compressor 1, a condenser 2, a receiver 3, an electromagnetic expansion valve 6 and a check valve 8 are disposed in an engine room, a front side evaporator 5 and an expansion valve 4 are disposed in the front side room, and a rear side evaporator 7 is disposed in the rear side room. When performing air-conditioning only in the front side, the pipe for the rear side evaporator 7 is shut off in the engine room by means of a channel open/shut function of the electromagnetic expansion valve 6 and a function of the check valve 8, so that the refrigerant to be used in the front side is not held in the pipe, thus preventing the lack of cooling power due to the decrease of a circulating rate of the refrigerant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for an automobile, and more particularly to an air conditioner for an automobile having an evaporator on each of a front side and a rear side and capable of separately adjusting the temperature on the front side and the rear side. Regarding the device.

[0002]

2. Description of the Related Art Some automotive air conditioners have a front side and a rear side which are capable of separately adjusting the temperature in the room. In such an automobile air conditioner, an evaporator that is an indoor heat exchanger is provided on each of the front side and the rear side. These evaporators are connected in parallel in the refrigeration cycle, and the temperature of the room air that is heat-exchanged in each evaporator can be adjusted by adjusting the amount of the refrigerant that flows through them.

An expansion valve regulates the flow rate of the refrigerant sent to the evaporator. The expansion valve is generally driven by a power element that operates by sensing a change in the temperature and pressure of the low-pressure refrigerant that is heat-exchanged with room air and sent from the outlet of the evaporator, and the flow rate of the refrigerant sent to the evaporator. Are in control.

Here, when air conditioning is performed only on the front side and not on the rear side, it suffices to allow the refrigerant to flow only to the evaporator on the front side and prevent the refrigerant from flowing to the evaporator on the rear side. . As an expansion valve having a function capable of stopping such a flow of the refrigerant on the rear side, Japanese Patent Laid-Open No. 11-242242
An expansion valve with a solenoid valve described in Japanese Patent No. 325659 is known.

This expansion valve with a solenoid valve is provided in the evaporator on the rear side so that the low-pressure refrigerant passage between the expansion valve and the inlet of the evaporator can be forcibly closed by the solenoid valve. I have to. Thus, when air conditioning on the rear side is not required, the solenoid valve closes the low-pressure refrigerant flow passage so that the refrigerant does not flow into the evaporator.

However, by closing the inlet of the rear side evaporator with a solenoid valve, the refrigerant does not flow into the rear side evaporator, but if only the front side evaporator is used, then Refrigerant flowing out of the outlet of the front side evaporator flows back to the outlet of the rear side evaporator, enters the inside of the rear side evaporator, accumulates in the rear side evaporator, and accumulates in the front side refrigeration cycle. The refrigerant circulation amount decreased, and the cooling power sometimes became insufficient.

Therefore, the applicant of the present application filed Japanese Patent Application No. 2000-3.
In the specification of 88102, a refrigerant outlet pipe communicating from a rear evaporator to an outlet of a front evaporator is provided with a function of a one-way valve so that the refrigerant flowing out of the outlet of the front evaporator is discharged to the rear side. We have proposed a solenoid valve with a non-return function that prevents backflow to the outlet of the evaporator.

[0008]

However, the evaporator on the rear side is connected to the outlet of the liquid receiver provided in the engine room and the outlet of the evaporator on the front side by long pipes, respectively, and these Although the piping is small compared to the capacity of the evaporator, it has a certain amount of capacity, so that capacity gives a space where the refrigerant accumulates when the evaporator on the rear side is not used, There has been a problem that the amount of refrigerant circulation in the refrigeration cycle is reduced and the cooling power becomes insufficient.

The present invention has been made in view of the above points, and when the air conditioning is performed only on the front side, the air conditioner for automobiles in which the refrigerant is prevented from stagnation in the pipe connected to the evaporator on the rear side is provided. The purpose is to provide a device.

[0010]

In order to solve the above problems, according to the present invention, a second expansion device and a rear evaporator having a flow passage opening / closing function in parallel with the first expansion device and the front evaporator are provided. A second expansion device, and a check valve for preventing refrigerant from flowing backward from the outlet of the front evaporator to the outlet of the rear evaporator. An air conditioner for a vehicle is provided, which is characterized by being installed in an engine room.

According to such an automobile air conditioner, the second expansion device and the check valve are installed in the engine room, so that when air conditioning is performed only on the front side, the air is directed toward the rear evaporator. The pipes connected are by the flow path opening / closing function of the second expansion device, and the pipes connected from the rear side evaporator to the outlet side of the front side evaporator are by the function of the check valve. Since the refrigerant flow path is blocked in the room, the refrigerant used for air conditioning on the front side will not stagnate in the pipe between the engine room and the evaporator for the rear, and the refrigerant circulation amount in the refrigeration cycle on the front side will be reduced. It will not decrease and the front air conditioning will not become cold enough.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings, taking as an example the case where the present invention is applied to a vehicle having a front engine.

FIG. 1 is a diagram showing a system configuration of an automobile air conditioner according to the present invention. A refrigeration cycle of an automobile air conditioner includes a compressor 1 for compressing a refrigerant, a condenser 2 connected to a discharge side of the compressor 1 for cooling and condensing a high temperature / high pressure refrigerant, and a condenser 2 for the condenser 2. The liquid receiver 3 is connected to the downstream side to separate gas and liquid from the condensed refrigerant and store the liquid refrigerant. The outlet side of the liquid receiver 3 is divided into two, and one of the expansion valve 4 and the expansion valve 4 adiabatically expands the liquid refrigerant supplied from the liquid receiver 3 into a low temperature / low pressure refrigerant. It is connected to the suction side of the compressor 1 via a front side evaporator 5 that exchanges heat between the supplied refrigerant and room air, and the other side is an electromagnetic expansion valve 6 and a rear side evaporator 7 having an electromagnetic opening / closing function. Also, it is configured so as to merge with the downstream side of the front side evaporator 5 via the check valve 8.

Here, the compressor 1, the condenser 2, the liquid receiver 3,
The electromagnetic expansion valve 6 and the check valve 8 are installed in the engine room on the front side of the automobile, and the front side evaporator 5 is installed.
The expansion valve 4 is installed in the front room, and the rear evaporator 7 is installed in the rear room.

In the above air conditioner for an automobile that performs air conditioning on the front side and the rear side, for example, when air conditioning is performed on the front side and the rear side at the same time, the refrigerant flow rate is accurately controlled by giving priority to the front side. Regarding air conditioning on the rear side, simple control is generally performed.

When air conditioning is performed on the front side and the rear side at the same time, the refrigerant compressed by the compressor 1 passes through the condenser 2 and the liquid receiver 3, while one passes through the expansion valve 4 and the front side evaporator 5. Back to compressor 1, on the other hand,
Returning to the compressor 1 through the electromagnetic expansion valve 6, the rear evaporator 7 and the check valve 8. When air conditioning is performed only on the front side, the refrigerant compressed by the compressor 1 returns to the compressor 1 through the condenser 2, the liquid receiver 3, the expansion valve 4, and the front side evaporator 5.

At this time, the refrigerant flowing from the liquid receiver 3 to the expansion valve 4 is evaporated at the rear side because the electromagnetic expansion valve 6 is closed at the engine room side end of the pipe toward the rear side evaporator 7. Refrigerant does not flow into the pipe to the vessel 7. Further, a check valve 8 is provided at the engine room side end of the pipe that joins the rear evaporator 7 with the outlet pipe of the front evaporator 5.
Prevents the refrigerant from flowing back to the pipe from the rear side evaporator 7. As a result, when air conditioning is performed only on the front side, the refrigerant stagnates in the pipe provided between the engine room and the rear evaporator 7, and the amount of the refrigerant flowing through the front side refrigeration cycle becomes insufficient. It is possible to prevent such a situation, and it is possible to prevent a shortage of cooling power in the air conditioning on the front side.

Next, a specific structural example of the electromagnetic expansion valve 6 will be described. FIG. 2 is a vertical sectional view showing a configuration example of the electromagnetic expansion valve. In the electromagnetic expansion valve 6, an inlet hole 11 is formed at the lower end of a body 10, and an outlet hole 12 is formed from the lower side of the body 10. A strainer 13 is fitted in the inlet hole 11. A valve seat 15 is formed integrally with the body 10 in the middle of the refrigerant flow path 14 communicating from the inlet hole 11 to the outlet hole 12, and a ball-shaped valve body 16 is arranged facing the valve seat 15 from the downstream side. ing. The valve body 16 is held by a valve pushing member 17 so as not to be rolled by the refrigerant flowing through the valve hole of the valve seat 15.
The valve pushing member 17 has a piston-like shape, and is fitted and arranged in a cylinder formed in the body 10 so as to be movable back and forth in the axial direction. The body 10 near the cylinder accommodating the valve pushing member 17 is provided with a communication hole 18 for equalizing all the pressures on the downstream side of the valve.

On the body 10 above the valve pushing member 17,
The lower end of the sleeve 20 is fixed via the bearing 19. The bearing 19 also has a communication hole 21 for equalizing pressure. A core 22 is fixedly arranged on the upper end of the sleeve 20. Sleeve 20 between bearing 19 and core 22
A plunger 23 is arranged therein so as to be movable back and forth in the axial direction thereof, and the plunger 23 is supported by a shaft 24 whose both ends are axially supported by a bearing 19 and a recess formed in the core 22. A spring 25 is arranged between the plunger 23 and the core 22 to urge the valve body 16 in a direction to be seated on the valve seat 15 via the plunger 23, the shaft 24 and the valve pushing member 17. Sleeve 20
An electromagnetic coil 26 is provided on the outer periphery of the electromagnetic coil 26, and the electromagnetic coil 26 is surrounded by a yoke 27.

In the electromagnetic expansion valve 6 thus constructed, when the electromagnetic coil 26 is not energized and is off,
As shown in FIG. 2, the plunger 23 has a spring 25.
The valve body 1 is urged downward by the
6 is pushed down through the shaft 24 and the valve pushing member 17 in the figure, so that it is seated on the valve seat 15 and is in the valve closed state. When the electromagnetic coil 26 is energized and is turned on, the plunger 23 resists the biasing force of the spring 25 and
Is adsorbed on. As a result, the valve body 16 and the valve pushing member 17 supporting the valve body 16 are free to move in the axial direction. Here, when the refrigerant is supplied from the inlet hole 11, the valve body 16 is pushed upward by the pressure of the refrigerant, and a throttle channel having a predetermined channel cross-sectional area is formed between the valve element 16 and the valve seat 15. Comes to form.

Since such an electromagnetic expansion valve 6 is an on / off valve, superheat on the outlet side of the rear evaporator 7 cannot be controlled. Therefore, the control of the flow rate of the refrigerant by the electromagnetic expansion valve 6 is performed by controlling the on time and the off time of the electromagnetic expansion valve 6 according to the refrigeration load on the rear side. The on-time and the off-time are determined so as to be the refrigerant flow rate corresponding to the load predicted from the room temperature on the rear side, the rotation speed of the fan motor that allows air to pass through the rear evaporator 7, the outside air temperature, and the like. For example, if the predicted load is maximum, the on-time is 100
%, The off time is set to 0%, and when the load is half, the on time and the off time are controlled to be 50%.

FIG. 3 is a diagram showing another system configuration of the automobile air conditioner according to the present invention, and FIG. 4 is a diagram showing characteristics of the electromagnetic expansion valve. In FIG. 3, elements that are the same as or equivalent to the elements shown in FIG. 1 are assigned the same reference numerals and detailed explanations thereof are omitted.

According to this system, the temperature sensor 6a is provided on the outlet side of the electromagnetic expansion valve 6 installed in the engine room on the front side of the automobile, and the temperature sensor 8a is provided on the inlet side of the check valve 8. The electromagnetic expansion valve 6 is used as a differential pressure control valve capable of arbitrarily setting the front-rear differential pressure between the inlet and the outlet by the supplied current.

Since the outlet of the electromagnetic expansion valve 6 is saturated, the temperature sensor 6a can detect the refrigerant temperature at the outlet of the electromagnetic expansion valve 6 to know the refrigerant pressure from the refrigerant temperature. . Further, the temperature sensor 8a can know the refrigerant temperature on the inlet side of the check valve 8, that is, the refrigerant temperature on the outlet side of the rear evaporator 7. Since the temperature and pressure of the refrigerant at the outlet of the rear side evaporator 7 can be known by these temperature sensors 6a and 8a, the degree of superheat of the refrigerant at the outlet of the rear side evaporator 7 as in a normal temperature type expansion valve. Will be able to control.

The electromagnetic expansion valve 6 uses the electromagnetic valve having the configuration shown in FIG. 2 as a differential pressure control valve, and has a predetermined degree of superheat based on the evaporation state of the refrigerant at the outlet of the rear evaporator 7. The pressure difference between the front and rear is set so that the flow rate of the refrigerant is controlled. The differential pressure ΔP across the electromagnetic expansion valve 6 is, as shown in FIG.
Is set by the current value i supplied to the
Is determined by the temperature and pressure of the refrigerant at the outlet of the rear side evaporator 7 obtained from the two temperature sensors 6a and 8a.

Here, in the electromagnetic expansion valve 6, when the current value i is zero, that is, when the electromagnetic coil 26 is not energized, the differential pressure across the electromagnetic expansion valve 6 is unlikely to exist in the system. It is set to a high differential pressure. For example, when Freon HFC-134a is used as the refrigerant, the differential pressure across the electromagnetic expansion valve 6 is generally said to be about 2.5 MPa at the maximum, so it is much higher than this, for example, about 3 MPa. Set it. As a result, when the electromagnetic coil 26 is not energized, the electromagnetic expansion valve 6 is left closed and can be fully closed. That is, the electromagnetic expansion valve 6 is an expansion valve having a fully closing function.

With the above configuration, even in the air conditioning on the rear side, as in the front side, the flow rate can be adjusted so that the evaporation state of the refrigerant at the outlet of the rear side evaporator 7 has an appropriate degree of superheat. When the air conditioning on the rear side is not performed, the electromagnetic expansion valve 6 itself is fully closed, so the refrigerant used for air conditioning on the front side is installed in the pipe between the electromagnetic expansion valve 6 in the engine room and the rear evaporator. No more falling asleep.

[0028]

As described above, according to the present invention, the expansion device for the rear and the check valve for preventing the reverse flow of the refrigerant from the outlet of the front side evaporator to the outlet side of the rear side evaporator are provided. It is configured to be installed in the engine room. This allows
When air conditioning is performed only on the front side, the piping connected to the rear side evaporator is connected to the outlet side of the front side evaporator by the function of opening and closing the flow path of the rear expansion device. In the pipes connected together, the refrigerant flow path is blocked in the engine room by the check function of the check valve, so that the refrigerant used for air conditioning on the front side is between the engine room and the evaporator on the rear side. Never fall asleep in a pipe. Therefore, the amount of refrigerant circulating in the front side refrigeration cycle will not decrease and the front side air conditioning will not have insufficient cooling power.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of an automobile air conditioner according to the present invention.

FIG. 2 is a vertical sectional view showing a configuration example of an electromagnetic expansion valve.

FIG. 3 is a diagram showing another system configuration of an automobile air conditioner according to the present invention.

FIG. 4 is a diagram showing characteristics of an electromagnetic expansion valve.

[Explanation of symbols]

1 compressor 2 condenser 3 liquid receiver 4 expansion valve 5 Front side evaporator 6 Electromagnetic expansion valve 6a Temperature sensor 7 Rear side evaporator 8 Check valve 8a Temperature sensor 10 body 11 entrance holes 12 exit holes 13 strainers 14 Refrigerant flow path 15 seat 16 valve body 17 Valve pushing member 18 communication holes 19 bearings 20 sleeve 21 communication holes 22 core 23 Plunger 24 shaft 25 springs 26 electromagnetic coil 27 York

Claims (4)

[Claims] 1. An automotive air conditioner configured by arranging a second expansion device having a flow path opening / closing function and a rear evaporator in parallel with the first expansion device and the front evaporator. 2. An air conditioner for a vehicle, characterized in that the expansion device of No. 2 and a check valve for preventing the refrigerant from flowing back from the outlet of the front side evaporator to the outlet side of the rear side evaporator are installed in the engine room. apparatus. 2. The second expansion device is an electromagnetic on-off valve that fully closes the flow path or adiabatically expands the refrigerant when on, and adiabatically expands the refrigerant or fully closes the flow path when off. The air conditioning system for an automobile according to claim 1. 3. A first temperature sensor for sensing an outlet temperature of the second expansion device, and a second temperature sensor for sensing an inlet temperature of the check valve, wherein the second expansion device is provided. ,
The superheat degree of the refrigerant at the outlet of the rear side evaporator is controlled by a current value determined by the temperature and pressure of the refrigerant at the outlet of the rear side evaporator obtained by the first and second temperature sensors when turned on. 2. The air conditioner for a vehicle according to claim 1, wherein the differential pressure control valve is a differential pressure control valve which is set to a front-rear differential pressure and which is set to a high differential pressure which is not possible in the system when the front-rear differential pressure is off. 4. A second expander installed in the engine room and having a function of opening and closing a flow path, in parallel with the first expander and the front evaporator, and installed in the rear evaporator and engine room. In the method for controlling an automobile air conditioner configured by arranging a check valve for preventing the refrigerant from flowing backward from the outlet of the front side evaporator to the outlet side of the rear side evaporator, the load on the rear side is A method of controlling an air conditioner for an automobile, characterized in that a flow rate control is performed by intermittently flowing a refrigerant to the rear side evaporator by predictably controlling the opening / closing of the second expansion device.